grandma vs grannie

grandma and grannie both are nouns.

Word	Noun	Adjective	Verb	Adverb
grandma	Yes	No	No	No
grannie	Yes	No	No	No

As nouns, grandma and grannie are synonyms defined as:

Other synonyms of grandma include gran, grandmother, granny, nan, nanna.

grandma (noun)	grannie (noun)
the mother of your father or mother	the mother of your father or mother